diff --git a/config/settings.defaults.js b/config/settings.defaults.js
index 51cb624..d051cea 100644
--- a/config/settings.defaults.js
+++ b/config/settings.defaults.js
@@ -76,6 +76,7 @@ if (process.env.DOCKER_RUNNER) {
       socketPath: '/var/run/docker.sock',
       user: process.env.TEXLIVE_IMAGE_USER || 'tex'
     },
+    optimiseInDocker: true,
     expireProjectAfterIdleMs: 24 * 60 * 60 * 1000,
     checkProjectsIntervalMs: 10 * 60 * 1000
   }